The invention relates to an arrangement for determining the effective playing time of a sporting team game, having a referee and a predetermined duration of play, in which interruptions of play are signalled acoustically by the referee and comprising at least one time measuring device which comprises an actuator input for the interruption and re-starting of the measurement, a receiver device for wireless signal transmission of which the output is connected to the actuator input, a portable transmitter device for the referee to give signals to the receiver device, and a switch device operable by the referee for the activation of the transmitter device and for the transmission of signals which interrupt and re-start the time measurement at the beginning and end respectively of each interruption of play.
In practice it has proved desirable to provide special measures for increasing the security of such arrangements against interference, to render impossible interference by interfering transmitters with the control of the time measurement. Moreover the signal transmission should be simplified. An object of the invention is to provide improved means for this purpose.